Characterization of an acid-tolerant β-1,4-glucosidase from Fusarium oxysporum and its potential as an animal feed additive.

An extracellular β-glucosidase (BGL) from Fusarium oxysporum was purified to homogeneity by a single chromatography step on a gel filtration column. The optimum activity of BGL on cellobiose was observed at pH 5.0 and 60 °C. Under the same conditions, the Km and Vmax values for p-nitrophenyl β- d-glucopyranoside and cellobiose were 2.53 mM, 268 U mg protein −1 and 20.3 mM, 193 U mg protein −1, respectively. The F. oxysporum BGL enzyme was highly stable at acidic pH ( t1/2 = 470 min at pH 3). A commercial BGL Novo188 (Novozymes) and F. oxysporum BGL were compared in their ability to supplement Celluclast 1.5 L (Novozymes). In comparison with the commercial Novo188 (267 mg g substrate −1), F. oxysporum BGL supplementation released more reducing sugars (330 mg g substrate −1) from cellulose under simulated gastric conditions. These properties make F. oxysporum BGL a good candidate as a new commercial BGL to improve the nutrient bioavailability of animal feed. [ABSTRACT FROM AUTHOR]